1. Field of the Invention
The present invention relates to an image capture device for shooting a color motion picture, and specifically to an image capture device capable of displaying, during image capture, a color motion picture in which a first color component and a second color component are picked up at different charge accumulation time periods.
2. Description of the Related Art
A system of capturing R (red), G (green) and B (blue) color components at different resolutions and different exposure time periods has been proposed. Technologies of separating incident light into, for example, a G component (first color component) and an R and B component (second color component) and picking up these two color components by use of different image sensors are disclosed in WO08/047,664, Japanese Laid-Open. Patent Publication No. 2008-211273, WO2009/019823, and WO2009/019824. When the G color component is picked up at a high resolution and a low frame rate, a necessary charge accumulation time period (exposure time period) and a necessary spatial resolution are obtained for the G color component. Therefore, a G image having a high S/N ratio can be obtained with a sufficient amount of light. By contrast, when the R and B color component is picked up at a low resolution and a high frame rate, an image having a high temporal resolution can be obtained for the R and B color component. By performing image processing on the color component image picked up at a high resolution and a low frame rate and the color component image picked up at a low resolution and a high frame rate, a color motion picture of a high resolution and a high frame rate can be recovered. WO2010/090025 discloses a technique of using a single-plate color image sensor for the above-described system.
When the above-described conventional technology is used for image capture of a moving subject, an image of a color component picked up at a short charge accumulation time period does not include much motion blur of the subject. However, an image of a color component picked up at a long charge accumulation time period includes relatively large motion blur of the subject. When these color component images are merely overlapped to create a color image, a color shift occurs due to the motion blur of the color component picked up at the long charge accumulation time period. When a color image created by merely overlapping color component images of a subject picked up by the above-described image capture system is displayed by an image capture and display device such as a viewfinder or the like, there is a problem that it is difficult to check the state of the subject due to the color shift. Regarding synthesis of a color image in which different color components are picked up at different charge accumulation time periods, a technology described in Japanese Laid-Open Patent Publication No. 2008-211273 is known. According to this technology, color component images picked up at a short charge accumulation time period are added each time when being read while a color component image picked up at a long charge accumulation time period is accumulated, and are output to a display device at the same timing as the color component image picked up at the long charge accumulation time period.
According to above-described conventional structure, an output of a color component picked up at a short charge accumulation time period is adapted to an output of a color component picked up at a long charge accumulation time period. As a result, the frame rate of the output color image is matched to the frame rate of the color component image picked up at the long charge accumulation time period. In this case, when the motion of the subject is large, there occurs a problem that the motion blur of the subject is conspicuous on the display device.
Meanwhile, for obtaining a high frame-rate color image with little motion blur of the subject, it is conceived to perform image processing for increasing the frame rate of the color motion picture to a high level and display the resultant color image on the display section. However, when a display image to be used for checking the subject during image capture is to be created, the image of the subject needs to be displayed in real time. For realizing this, a color image which has been processed to be increased in the frame rate needs to be displayed by the display device. This causes a problem that the display is delayed by the time required for the image processing.
The present invention has an object of providing an image capture device capable of displaying, during image capture, a color image picked up by an image capture system of picking up images of different color components at different charge accumulation time periods.